JPS6286080A - Release treating agent and preparing same - Google Patents

Abstract

PURPOSE:To efficiently obtain a release treating agent which exhibits excellent adhesion to a hydrophilic substrate, by reacting polyvinyl alcohol with an equivalent or excessive amt. of a long-chain alkyl isocyanate and saponifying the reaction product. CONSTITUTION:A polyvinyl alcohol having a degree of saponification of 10-90% is reacted with a 6-30 C long chain alkyl isocyanate (e.g., dodecyl isocyanate) in an amt. equivalent to or larger than that of the hydroxyl groups of the polyvinyl alcohol. The reaction product is saponified in the presence of an alkali to obtain an intended release treating agent based on polyvinyl alcohol and a long-chain alkyl isocyanate and having a hydroxyl group content of 5-90% based on the vinyl unit. The treating agent imparts a good releasability to an adhesive tape and excellent adhesion to a hydrophilic substrate, such as cellophane substrate, due to the presence of the hydroxyl groups in its molecule.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to the releasability of polyvinyl alcohol-long chain alkyl isocyanate (polyvinyl carbamate) having hydroxyl groups in the molecule and exhibiting good adhesion to aqueous substrates. This invention relates to a processing agent and its manufacturing method.

The back side of the base material in conventional technology adhesive tapes, adhesive tapes, etc. is usually
The mold has been released using a release agent.

Among the performance requirements for this releasable treatment agent or its treatment layer, is it good for the base material? : It has a youthful appearance and may not fall off easily.

Conventionally, as a polyvinyl alcohol single-chain argyl isocyanate-based stripping agent, a type that does not have a hydroxyl group in the molecule is obtained by reacting polyvinyl alcohol and its hydroxyl group with octadecyl isocyanate having an IA or higher. (Special Publication No. 29-7333)
(Japanese Patent Publication No. 34-3382).

Problems to be Solved by the Invention However, conventional polyvinyl alcohol-long chain alkyl isocyanate-based release agents do not have practically satisfactory adhesion to substrates, especially parent and aqueous substrates such as cellophane and paper. The problem was that it was not possible. That is, when the releasable treatment agent is applied to a hydrophilic base material,
There is a problem in that the treated layer easily falls off from the base material due to thermal changes, friction, or the like.

Means to Solve the Problems The present inventors have overcome the above problems and created a material that has excellent adhesion even to hydrophilic substrates, smoothness during unwinding, heat resistance, non-aging properties, As a result of intensive research to develop a releasable treatment agent that can obtain a treated layer with excellent peelability such as non-staining of the adhesive surface, we found that polyvinyl alcohol with a hydroxyl group in the molecule - long chain alkyl It was discovered that the purpose could be achieved using isocyanate-based products, and the present invention was completed.

That is, the present invention requires that the prisoner molecule has a hydroxyl group (
BIIu has good adhesion to aqueous substrates and (
C) A stripping treatment agent characterized by being a product obtained by reacting polyvinyl alcohol with a long-chain alkyl isocyanate, and polyvinyl alcohol with a saponification degree of 10 to 95%, and an equivalent or more amount of hydroxyl groups in the polyvinyl alcohol. The present invention provides a method for producing a polyvinyl alcohol-long-chain alkyl isocyanate-based stripping treatment agent, which comprises saponifying a product obtained by reacting the product with a long-chain alkyl isocyanate.

Hereinafter, the processing agent of the present invention will be explained based on the method of the present invention, which is an example of its manufacturing method.

In the method of the present invention, first, polyvinyl alcohol and long-chain alkyl isocyanate are reacted by a conventional method. In this case, the long-chain alkyl isocyanate is used in an amount equal to or more than the equivalent amount, preferably in an amount equivalent to the hydroxyl group of the polyvinyl alcohol, from the viewpoint of production efficiency. As a result, a compound having no or substantially no hydroxyl groups, which is obtained by a grafting reaction of a long-chain alkyl isocyanate via the hydroxyl system of polyvinyl alcohol, is obtained.

The polyvinyl alcohol used in the above reaction has a degree of saponification of 10 to 95%, preferably 20 to 90%.
, the degree of polymerization is 200 to 3000, preferably 300 to 200
The one with 0 is both light. If the degree of saponification is less than 10, the introduction of long chain alkyl units will be insufficient and the resulting releasable treatment agent will have poor releasability (excessive adhesive strength).
On the other hand, if it exceeds 95%, the reaction with the long-chain alkyl isocyanate will be delayed due to its large crystallinity, which is practically undesirable. On the other hand, if the degree of polymerization is less than 200, the resulting stripping agent will have poor heat resistance. On the other hand, if it exceeds 3,000, the resulting releasable treatment agent will have poor solubility, which may have an undesirable effect on workability during application to a substrate.

As the long chain alkyl isocyanate, for example, dodecyl
Rain cyanate, tridecyl isocyanate, tetradecyl isocyanate, pentadecyl isonanate,
Hexadecyl isocyanate, hexadecyl isocyanate, octadecyl isocyanate, nonadecyl isocyanate, eicosyl isocyanate, heneicosyl isocyanate, tocosyl isocyanate, tocosyl isocyanate, tetradecyl isocyanate, bentacyl isocyanate, hexadecyl isocyanate, octadecyl isocyanate, nonadecyl Those having an alkyl group having 6 to 30 carbon atoms, preferably 16 to 26 carbon atoms, such as isocyanate and triacontylisocyanate, are preferably used. If the number of carbon atoms is 5 or less, the resulting releasable treatment agent 1 will have poor peeling performance, and if the number of carbon atoms is 31 or more, the ladle feedability will be poor.

Next, the reaction product of polyvinyl alcohol and long-chain alkyl isocyanate obtained by the above reaction is saponified. As a result, hydroxyl groups are introduced into the reaction product. Saponification is 7. This is preferably carried out in an organic solvent in the presence of an alkali such as potassium oxide or aqueous ammonia.

The rate of introduction of hydroxyl groups into the reaction product by saponification is:
5 based on vinyl units in polyvinyl alcohol
~90$, preferably 10-70%. That is,
It is appropriate that 5 to 90% of the vinyl units (including long chain alkylated moieties) in the polyvinyl alcohol have hydroxyl groups. 5 vinyl units with hydroxyl group
If it is less than 90%, the resulting releasable treatment agent will have insufficient adhesion to the hydrophilic substrate, while if it exceeds 90%, the resulting releasable treatment agent will have poor water resistance, which is preferable. do not have.

As described above, the releasable treatment agent of the present invention, which has a hydroxyl group in its molecule and has good adhesion to hydrophilic substrates, is obtained by reacting polyvinyl alcohol with a long-chain alkyl isocyanate. It will be done.

Effects of the Invention The releasable treatment agent of the present invention has a -4-J hydrophilic group in its molecule, so it has excellent adhesion to hydrophilic substrates.

It also has the advantage that the adhesion-peel balance can be controlled by changing the introduction rate of long-chain alkyl isocyanate.

On the other hand, the method of the present invention has the advantage that it is possible to easily control the introduction rate of long-chain alkyl isocyanate, and that the desired stripping treatment agent can be obtained with high production efficiency.

Examples Example 1 50 parts (parts by weight, the same applies hereinafter) of polyvinyl alcohol with a 7-part content of 300% and a saponification degree of 20'l, xylene 132, a 500 cc four-tube flask equipped with a reflux condenser and a water metering receiver. and heated the system to 140°C with stirring.
The mixture was heated for 2 hours to dissolve the polyvinyl alcohol and remove water from the system or polyvinyl alcohol. Thereafter, the system was cooled to 12,000 ℃, and 38 parts (equivalent) of octadecyl ylananate and 0.0 parts of organotin catalyst were added to the system.
Add 3 parts and allow to react. The progress of the reaction in the system is confirmed by quantifying the isocyanate groups in the system, and the end point of the reaction is determined when no isocyanate groups remain.

Next, the system was cooled to 40'C with stirring, and then a solution prepared by dissolving 14.4 parts of potassium hydroxide in 105 parts of methanol and 46 parts of water were added to carry out a saponification reaction for 5 hours.

The obtained reaction product is precipitated in methanol to obtain a crude product. The hydroxyl group contained per molecule of this purified product was 80% based on vinyl units. This hydroxyl group was quantitatively determined by the following method. In other words, create a solution of phthalic anhydride 2y dissolved in dehydrated pyridine log/? Dissolve sample 1y in this, heat in a hot water bath for 1 hour, add 5Q+m/ of distilled water, heat for 10 minutes, and then cool. Phenolphthalein K for this liquid
Titrate with 0.5N caustic potassium aqueous solution as fH indicator.

Examples 2 to 5, Comparative Example 1.2 A stripping treatment agent (i-) was obtained as a reaction product according to Example 1 using the compounding ratios shown in the table. It's something like that.

A toluene solution containing 1 weight of the release treatment agent obtained in the evaluation test examples and comparative examples was prepared, and this was applied to one side of a cellophane film at a coating amount of 0.05 mm/m', and dried. A releasably treated film was obtained.

Next, the treatment βi! of the treated film is determined. El'li withered J1
9 tape (cellophane tape black 29, Nitto Electric Industry Co., Ltd.)
After pasting and storing at 20'C for 24 hours,
The viscous FT tape was peeled off under the conditions of beer and a tensile speed of 30011/min, and its peel strength was examined.

On the other hand, the releasable treated film was immersed in water for 3 minutes, taken out, and the peeling properties of the treated layer on the substrate were examined by checking whether the treated layer peeled off or not. In addition, the evaluation was made as ○ when there was no peeling and as × when there was peeling.

The results are shown in the table.

*I: Octadecylisoneanate *2: Hexadecyl isocyanate *3: Eicosyl isocyanate From the table, the hydroxyl group-containing releasable treatment agent of the present invention has good releasability to adhesive tapes and is suitable for cellophane base materials. It can be seen that it has excellent adhesion to the substrate and does not easily fall off from the substrate due to moisture.

In addition, the introduction rate of long-chain alkyl isocyanate is 1c.
Therefore, it can be seen that the peel strength (adhesion - peel strength) can be controlled.

Claims (1)

[Claims] 1. A releasable treatment agent having the following characteristics (A) to (C). (A) Having a hydroxyl group in the molecule. (B) It has good adhesion to a hydrophilic base material. (C) A product obtained by reacting polyvinyl alcohol with a long-chain alkyl isocyanate. 2. The content of hydroxyl groups based on vinyl units is 5 to 90%
The processing agent according to claim 1. 3. The processing agent according to claim 1, wherein the polyvinyl alcohol has a degree of polymerization of 200 to 3,000. 4. The treatment agent according to claim 1, wherein the long-chain alkyl isocyanate has an alkyl group having 6 to 30 carbon atoms. 5. A polyvinyl alcohol characterized by saponifying a product obtained by reacting polyvinyl alcohol with a saponification degree of 10 to 95% with a long-chain alkyl isocyanate equivalent to or more than the hydroxyl group in the polyvinyl alcohol. A method for producing a long-chain alkyl isocyanate-based stripping agent. 6. The method according to claim 5, wherein the saponification is carried out in the presence of an alkali.